Needles may be used in a variety of medical procedures, some of which may require careful attention to the depth to which the needle may be inserted into the patient. For example, infants with fever or signs of a serious bacterial infection routinely undergo a full sepsis evaluation, including a lumbar puncture (LP) procedure. The LP procedure involves a technique for collecting cerebrospinal fluid (CSF) from a patient, and is commonly to identify meningitis in young infants. Such procedures can be difficult, even for experienced physicians and particularly on infants 90 days of age and younger. Unsuccessful LP procedures may be defined by the collection of bloody CFS (such as by puncturing a subdural vessel by advancing the needle too far) or by the failure to collect any fluid.
There are two techniques that have been described that include performing LP procedures in conjunction with sonography (ultrasound). In one technique, the LP procedure involves monitoring the progress of the needle with the aid of ultrasound as the needle is advanced into the spinal canal. This technique may require significant training, dexterity, multiple providers, and a sterile environment. In another technique, the sonography is performed just prior to the LP procedure, and the important landmarks are identified and the patient's skin is marked to assist the provider/operator with the LP procedure.